Re: [PATCH 64/86] IP_GRE: Fix kernel panic in IP_GRE with GRE csum.

From: Steven Rostedt
Date: Wed Mar 27 2013 - 00:35:23 EST


On Wed, 2013-03-27 at 04:28 +0000, Ben Hutchings wrote:
> On Tue, 2013-03-26 at 13:22 -0400, Steven Rostedt wrote:
>
> > 3.6.11.1 stable review patch.
> > If anyone has any objections, please let me know.
> >
> > ------------------
> >
> > From: Pravin B Shelar <pshelar@xxxxxxxxxx>
> >
> > [ Upstream commit d0a7cc630a337b0f56dc145e7eb6232852b14dd4 ]
> >
> > Due to IP_GRE GSO support, GRE can recieve non linear skb which
> > results in panic in case of GRE_CSUM. Following patch fixes it by
> > using correct csum API.
> >
> > Bug introduced in commit 6b78f16e4bdde3936b (gre: add GSO support)
>
> That commit went into 3.7, so I don't think this fix is needed for 3.6.

Ah, you're saying that because 6b78f16e4bdde3936b wasn't in 3.6, this
isn't needed for 3.6 either.

I created scripts to find the commits that made it into 3.7 and 3.8 that
were not added to 3.6 and just cherry-picked them. Unless they failed
because of a conflict, I really didn't look hard at them.

Thanks, I guess I can remove this change then.

-- Steve

>
> Ben.
>
> > Signed-off-by: Pravin B Shelar <pshelar@xxxxxxxxxx>
> > Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
> > Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
> > ---
> > net/ipv4/ip_gre.c | 6 +++++-
> > 1 file changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
> > index b062a98..3ee08ce 100644
> > --- a/net/ipv4/ip_gre.c
> > +++ b/net/ipv4/ip_gre.c
> > @@ -946,8 +946,12 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
> > ptr--;
> > }
> > if (tunnel->parms.o_flags&GRE_CSUM) {
> > + int offset = skb_transport_offset(skb);
> > +
> > *ptr = 0;
> > - *(__sum16 *)ptr = ip_compute_csum((void *)(iph+1), skb->len - sizeof(struct iphdr));
> > + *(__sum16 *)ptr = csum_fold(skb_checksum(skb, offset,
> > + skb->len - offset,
> > + 0));
> > }
> > }
> >
>


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